function basePath(){
    var curWwwPath = window.document.location.href;
    var pathName =  window.document.location.pathname;
    var pos = curWwwPath.indexOf(pathName);
    var localhostPath = curWwwPath.substring(0,pos);
    var projectName = pathName.substring(0,pathName.substr(1).indexOf('/')+1);
    return (localhostPath + projectName);
}
function download(examname) {
    $(" #download").hide();
    $('.breadcrumb').hide();
    $('#hr').hide();
    $('#father').removeClass('father');
    $('#father').attr('style', 'background-color: #ffffff;');
    html2canvas(document.body, {
        onrendered: function (canvas) {

            var contentWidth = canvas.width;
            var contentHeight = canvas.height;

            //一页pdf显示html页面生成的canvas高度;
            var pageHeight = contentWidth / 592.28 * 841.89;
            //未生成pdf的html页面高度
            var leftHeight = contentHeight;
            //页面偏移
            var position = 0;
            //a4纸的尺寸[595.28,841.89]，html页面生成的canvas在pdf中图片的宽高
            var imgWidth = 595.28;
            var imgHeight = 592.28 / contentWidth * contentHeight;

            var pageData = canvas.toDataURL('image/jpeg', 1.0);

            var pdf = new jsPDF('', 'pt', 'a4');

            //有两个高度需要区分，一个是html页面的实际高度，和生成pdf的页面高度(841.89)
            //当内容未超过pdf一页显示的范围，无需分页
            if (leftHeight < pageHeight) {
                pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight);
            } else {
                while (leftHeight > 0) {
                    pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
                    leftHeight -= pageHeight;
                    position -= 841.89;
                    //避免添加空白页
                    if (leftHeight > 0) {
                        pdf.addPage();
                    }
                }
            }

            pdf.save('历史试卷-' + examname + '.pdf');

        }
    });

    $('#father').addClass('father');
    $('#father').removeAttr('style');
    $(" #download").show();
    $('.breadcrumb').show();
    $('#hr').show();
}